Question

Calculate the number of molecules in 54 gm of $H_{2}O$.

Answer 1

$\mathrm{Number}\mathrm{of}\mathrm{molecules}=\frac{(\mathrm{Avogadro}\mathrm{number}\times \mathrm{Given}\mathrm{mass})}{\mathrm{Gram}\mathrm{molecular}\mathrm{mass}}\mathrm{Number}\mathrm{of}\mathrm{molecules}\mathrm{of}\mathrm{water}=6.023\times {10}^{23}\times \frac{54}{18}=18.069\times {10}^{23}\mathrm{molecules}$